It has been stated in various publications, for example in a Scholler article in Chem. Zentr. 1939; 11, p. 1402-3, and in an article reported in CA 50, 8143d, Osborne et al, Anal. Chem. Vol. 28, pp. 211-215 (1956), that tobacco smoke may contain small amounts of hydrogen cyanide. Two patents to Keith, U.S. Pat. Nos. 3,251,365 and 3,460,543, and Litzinger, U.S. Pat. No. 3,716,063 also mention the presence of hydrogen cyanide in tobacco smoke and the Keith patents further discuss the possible effects of this gas from a physiological standpoint.
Selective removal of hydrogen cyanide from cigarette smoke by means of special filter compositions has been proposed on various occasions. Alkaline additives such as alkali metal carbonates and the like have been applied to conventional filter materials in efforts to remove or absorb any hydrogen cyanide contained in tobacco smoke. Activated carbonaceous material with a surface treatment of copper oxide has also been proposed for hydrogen cyanide removal. In Keith et al patent, U.S. Pat. No. 3,251,365 and in another Keith patent, U.S. Pat. No. 3,460,543, the use of various metal oxides, namely oxides of cobalt, copper, zinc or iron, on a carrier for removal of hydrogen cyanide is disclosed. In a more recent patent, Horsewell et al, U.S. Pat. No. 3,550,600, zinc acetate in admixture with an organic or inorganic base on a smoke filter paper or cellulose acetate filter support is described as being effective in the removal of various gaseous components, including hydrogen cyanide, from tobacco smoke. In the Horsewell et al patent, the examples given indicate a reduction of from about 57% to as high as 85% of the original hydrogen cyanide concentration in the tobacco smoke.
An object of the present invention is to provide a method and means for the colorimetric detection of cyanides.
Another object of the present invention is to provide a method and means for selectively removing cyanides, and particularly hydrogen cyanide, from gases.
A further object of the present invention is to provide a method and means for removing a major amount of any hydrogen cyanide which may be present in tobacco smoke.
A still further object of the present invention is to provide novel compositions of matter having utility as selective filtrants for cyanides from other gases.
These and still other objects will be discussed more fully in the description of the invention which follows.